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Presenter: Brad Buckham - Department of Mechanical Engineering
Supervisor:

Date: Thu, March 13, 2003
Time: 15:30:00 - 16:30:00
Place: EOW 430

ABSTRACT

ABSTRACT

Through the real-time telemetry afforded by the tether of a remotely operated vehicle (ROV), a human operator can control the vehicle motion, and the vehicle's robotic manipulators, through haptic and visual interfaces. Given the need for human judgment in the control of interactive tasks, and the lack of any wireless alternative, the tether will remain a necessity for the foreseeable future. Unfortunately, environmental forces that accumulate over the tether significantly affect ROV motion and complicate the job of the human pilot. Continuing efforts to establish a more continual human presence in the deep ocean are requiring a drastic increase in the number of remotely operated vehicle (ROV) deployments to the ocean floor. The focus of the work presented in this thesis is the development of a numerical tether dynamics model for application in the simulation of ROV s for pilot training.

Given the low-tension state of the ROV tether, it is necessary to include representations of the tether's bending and torsional stiffness to accurately capture the tether dynamics. Expanding the tether motion equations, it is shown that the low-tension bending and torsional effects are dependent on the curvature and torsion of the tether lay as well as the forces and torques applied at the tether boundaries. Applying existing non-linear finite elements to the low-tension tether problem, the state vector of the assembled system doubles in size compared to that of a popular cable modelling approach, the lumped mass method. Exploiting characteristics of the typical tether loading, a novel curvilinear element geometry is applied that allows the higher order shape information to be resolved while preventing such growth of the system equations. The low-tension model is shown to allow element size increases of 50% over linear lumped mass methods while the compact state representation reduces run times by up to 70% over alternative low-tension approaches.

FREE AND OPEN TO THE PUBLIC
Coffee and Cookies Will be Provided

For Further Information Please Contact: Brad Buckham (721-6035)